There is a continuing concern in the drug industry to package medications in a manner which will prevent easy access to them by children. The reason for this concern is obvious. If a package containing medications can be opened easily by a child, a serious risk of overdose exists. This can result in severe harm, or even death to the child.
It is known to package tablets, capsules and similar medications in pockets formed between flexible plastic sheets or films that are heat sealed, or otherwise secured together. Generally a plurality of individual units are separable from each other along lines of perforations. One such package is disclosed in U.S. Pat. No. 3,809,220, issued to Arcudi. The package disclosed in Arcudi is formed between opposed flexible plastic sheets, and includes a hidden tear zone, in the form of a slit located inwardly of the package's marginal edges. The slit is exposed by bending the package to thereafter permit easy opening of a central compartment in which the drug is packaged. As disclosed in Arcudi, individual packages are separably interconnected by lines of perforations. These lines of perforations include tabs, or bridge areas between discrete cuts, and these bridge areas are linearly aligned with the medicant-retaining compartment, or pocket in the adjacent and interconnected packaging unit. That is, projections perpendicular to the tabs or bridge areas intercept the tablet compartments.
It has been found that when tabs or bridge areas exist, they tend to become weakened areas in individual packages that are separated from the group. These tabs become weakened as a result of the tearing that takes place through them when the individual packages are separated. Apparently tearing through each bridge area provides a roughened edge that acts as a force-concentrating region when a child applies a tearing force to the edge of the package. It also has been found that notches or tears directed inwardly toward the medicant-retaining compartment can be formed at the junction of the bridge areas with slits or cuts of conventional lines of perforations. These notches or tears, once formed, can easily propagate, or be torn into the medicant-retaining compartment. Thus, even though the initially formed package system may have been child-proof, or tear-resistant, separation of an individual package along a line of perforations destroys this attribute.
U.S. Pat. No. 3,503,493, issued to Nagy, discloses a package that employs a blister 22 formed of relatively stiff material, such as polystyrene. This blister includes a depressed portion 23 to contain a drug therein. A flexible planar sheet material is sealed over the depressed portion to enclose the drug. A plurality of individual packets are interconnected through severance lines. One of the lines is formed by a plurality of slits 49 interconnected by tabs 51. Although it appears that the tabs may not be in linear alignment with the depressed portions 23 of the interconnected package units, there is actually no mention of the positional relationship of the slits and tab regions relative to the pockets or depressions 23 in the interconnected package units. Moreover, packages of the type disclosed in Nagy, i.e. those including a relatively stiff blister, do not pose the same child-access problems that are encountered in packaging systems formed between opposed, flexible planar plastic sheets. It is to these latter systems that the instant invention is directed. Stating this another way, the relationship of the slits 49 and interconnecting tabs 51 in the severance line relative to the pocket in the plastic blister has absolutely no effect on the child-resistant properties of the Nagy package. In Nagy the blister 22 is relatively stiff, and should be capable of adequately resisting a lateral tearing force imparted to the package by a child to prevent the child from tearing the package and gaining access to the drug. In Nagy the depressed compartment 23 is exposed by peeling the flexible cover sheet therefrom; not by tearing the package inwardly from the marginal edge in the manner employed to open packages formed by opposed, flexible planar sheets.
The following patents disclose various types of packaging systems; however, none of them deal with, or recognize the problem of the destruction of the tear-resistant properties of the package resulting from separating individual package units along interconnecting lines of perforations:
U.S. Pat. No. 3,809,221--Compere PA1 U.S. Pat. No. 3,924,746--Haines PA1 U.S. Pat. No. 3,941,248--Moser et al PA1 U.S. Pat. No. 4,011,949--Braber et al